For many years, fluid-applied membranes have been specified in commercial construction to perform in wall assemblies as air barriers, vapor barriers and water resistive barriers. These products are typically used over exterior sheathing or concrete block. Fluid-applied systems provide the following advantages over sheet applied systems:
- Improved air and water tightness
- Monolithic installation
- Sealing around brick ties and fasteners
Fluid-applied membrane products on the market are of diverse chemistries. Their manufacturers also specify installation at many different mil thicknesses. The mil thickness affects many properties of the installed system, including:
- Effective substrate coverage
- Effective seal around brick ties and fasteners
- Effective bridging of cracks
Specifiers of roofing systems would not consider classifying systems of significantly different thickness as equals. Yet fluid-applied membrane air barriers, whose specified mil thickness varies between 7 mils and 120 mils, are often placed in the same specification and classified as “equal”. In spite of the emergence of thin mil systems, the most common specified dry film thickness of fluid-applied membrane products is 40 mils. This matches the thickness of self-adhering roofing underlayment and self-adhering air/vapor barrier membranes, both of which have a very good track record of providing effective waterproofing in their respective applications.
As always, if you have any questions, please contact your local Carlisle rep to discuss in further detail.
As we begin to wind down another year, we realize with every job-site visit that our emphasis, as an industry, is growing on Building Envelope. Carlisle Construction Materials utilizes their key Design and Review Professionals in their roofing, belowgrade waterproofing, and wall assemblies to assist our Specifier Professionals with proper tie-in details to be used before and during construction. Details from roof-to-wall, wall to below-grade waterproofing, window openings, and any pipe or other penetrations are essential to specify and construct professionally.
The Building Envelope is the physical separator between the inside conditioned building, and the outside unconditioned space.
There are three basic elements; weather barrier, air barrier and thermal barrier. These three elements need to work together to provide a comfortable and efficient building. In addition, these products need to be compatible to work effectively.
The real ‘trick’, is to translate those specifications and tie-in details to the job site. With all the different trades involved to construct a successful building, communication between the design professional, the general contractor, sub-contractors and your manufacturer’s rep are essential.
If you would like more information on Building Envelope, or an AIA presentation at your office, please don’t hesitate to contact your local Carlisle representatives.
The requirement for the use of air barriers in new construction has been initiated as an energy-saving measure to reduce the amount of air leakage through the building envelope. The utilization of an air barrier is intended to limit the movement of warm air migration into the building during the summer and obstruct cold air migration into the building during the winter.
The new IECC Section C402.4 Air Leakage (Mandatory) does not apply to buildings in Climate Zones 1 through 3 and offers three compliance options for buildings in Climate Zones 4 through 8.
- First Option – Material
This option provides a list of pre-qualified building materials that includes adhered singly-ply membranes, built-up roof membranes and modified bituminous roof membranes. Mechanically fastened single-ply membranes are not included in this list.
- Second Option – Assembly
This option outlines a maximum air leakage of 0.04 cfm/ft2 at a pressure differential of 0.3 inches of water gauge when the roofing assembly is tested in accordance with ASTM E2357, ASTM E1677 or ASTM E283. (Note: None of these ASTM numbers relate to roofing.)
- Third Option – Whole Building Test
This option requires that the completed building shall be tested for air leakage and shall not exceed 0.40 cfm/ft2 at pressure differential of 0.3 inches of water gauge in accordance with ASTM E779.
To avoid adding an air barrier beneath a mechanically fastened single-ply roof, many roofing manufacturers have opted to explore option two, by independent third-party verification, following ASTM E1278, which tests for air permeance across a range of pressures. The results for Carlisle’s EPDM, TPO and PVC roofing membranes, when used in a mechanically fastened system, are significantly lower than the requirement of 0.04 cfm/ft2 The 2012 IECC requirement is intended for new construction in which a continuous air seal can be achieved, it has not been clarified for use in reroof and recover applications but is scheduled for discussion and possible inclusion in the 2015 edition of IECC. Carlisle will publish further updates on this issue as new information becomes available. . Documentation is available upon request.
For additional information, please contact your local Carlisle rep.